Process of operating gas-fired furnaces.



H. L, DOHERTYQ PROCESS OF OPERAHNG GAS FIHED FURNACES.

APPLICATION FILED MAR. 31| 1909; 1

Patented Een. 6, 1917.

` s SHEETS-sum1.

H. L. DOHERTY.

PROCESS oF OPERATING GAS HRED FURNACES.

' APPLICATION FILED MAR. 3l. 1909. 1,214,520. I Pmente Feb. 6,1m?.

3 SHEETS-SHEET 2.

u: f from/EV' H. L. D0HERTY. PROCESS 0F OPERATING GAS FIRED FURNACES.

- APPLICATION FILED MAR. S, i909- l,214,520. Patented Feb. 6,1917.

3 SHEETS-SHEET 3.

{Nl/ENIGE ratus, and the highest practicable recupera-v HENRY' L. DOHERTY, OENEW YORK, N. Y.

PRCESS OF OPERATING GAS-FIRED FURNAC'ES.

Specification of Letters Yetent.

Patented Feb. a, 191 7.

.application led March 31,. 15,308. Serial No. 486,889.'

To all whom t may cov' ern:

Be 1t known that I, HENRY L. Dormnrr, a citlzen of the United States, residing at N ew York city,in the county oiiNew YorkY and State ot' New York, have invented new and useful Improvements .in Processes of (')perating Gas-Fired Furnaces, of which the following is a specification.

My invention relates to a process of operating gas-fired furnaces and particularly, to the kind oi such 'processes wherein water vapor is the medium used to control the temperature of combustion in `the gas producing portion of theapparatus and is in the nature. oi an improvement to the method of operation of a gas bench disclosed in my Letters PatentNo. 993,322, dated May 23rd, 1911,.which process claimed-in my copeuding application Ser. No.- 622,549, the saule being a division ot the application "of said Letters `Patent.

The ob'ects of'mv invention are the Vdis- .l .Y i

tribution of the products of combustion trom the consuming portion of the apparatus between, the means for heating the air current supplied to the gas producing portion ot' the apparatus, and the means for heating the air current 'supplied to the gas consuming portion of the apparatus, in proportion to the quantityv of heat required in the respective air heating means, without affecting the'equal and uniform flow of the products of combustion through the gas consuming portion oi. the apparatus, the more efficient heating-of the air current supplied to the gas producing portion of the -appation of the sensible heat of the waste products of combustion. 9

My invention may be applied to any combinatini of a gas producer and furnace, in which/the two arer sov located in relation to each other that the'products of combustion tromf the furnace may be .introduced into recuperators for heating the air and water vapor for combustion in the gas producer and the air forcombustion in Vthe'furnace vatay substantially, the temperature at which y'they leave the furnace. 5o"

For purposes of illustration, l have shovh ,my mvention appliedto an apparatus for the manufacture of illuminating gas by the destructive distillation of coal-coinmonly known as a gas bench.

In the drawings, Figure 1 is a section through the gas bench on a plane parallel tothe front thereof, onthe line A-B, of Fig. 2. Fig. 2 isa longitudinal section through. the bench on the line C-l), of

Eig. l. F ig. 3 is a section through the sec- Fig. 1. Fig. et is a section through the primary air recuperator on the line G-H, of

Fig. l.k Fig. 5 shows a secondary air recuperator of a slightly dil'erent design. Fig. 6 i-s a section of a portion of the rear part ofthe bench, taken on a horizontal plane, whose intersections on the views shown in Figs.2, 3 'and 4t, are designated by the lines respectively.

Like numerals refer to like parts throughout the several views.

In the drawings, l is the gas producer'. 2 the grate thereof. 3 the primary air recuperator; 4; the secondary'air recuperator.

5 vare ports or openings. in the arch of the producer for the passage of the pro- 'ducer gas into the retort oven 6.

7, 7 are'the retorts. take-off lines 9.

1() .is the` uppermost waste gas flue of the 8, 8 the orifices in the v recuperator 4. 1l a iue connecting with l0,

through a port 12 and with the uppermost gas Hue Oof'the recuperator 3. '13 a port connecting 10 with a series of return-bend lines le.' 15, l5 ii each reouperator, leading to the stack of the bench.

16 is an adjustable damper' for regulating the flow of waste gas through the lue's 14;

17 is an opening with anadjustable damper, controlling the admission of air to the vrecuperator at. 18 a -lue leading the entering air to the back of the recuperator 4. -19 a series of return-bend flues. 2OA a port connectingthe uppermost fine 19, with an equalizing flue 21, having ports 22,' connecting it with a parallel distributing :fine 23.

e left-hand side of. the

.ondary air recuperator on the line E-F, of f l ues, one for los ing the air from `the lines 28 into the; cornf bastion chamber of the retort oven.

30 is the uppermost gas flue ofrecuperator'S, connected with and'discharging into' 4 the 'series of return-bend fines 3l.`

32 is an adjustable damper in ilue 9, on the same side of. the retort oven as recuperator 3, for regulating the volume of combustion gases passing therethrough.

33 is another similar damper corresponding to ifdamper 16 of recuperator 4.

34 is a water supply pipe connecting withI water pans 35 through theconnections 36, controlled by the valves 37. -The/water pans 35 are built into the recuperator 3 in such a manner that they divide it into a series of return-bend lines 38. The pans 35 are provided with overflow outlets 39, having their inlet orifices slightly ,raised above the bottom of the pans. A drain pipe discharges any excess of water from the lowermost of the pans 35.

4l is a port establishing communication between the uppermost of the lines 3S and a passage, or flue, 42, opening beneath the grate of the producer. f

43 is the lfuel charging ychute of the producer.

In Fig. 5, 44e is a secondary recuperator of a slightly diferent type from that shown in Figi 3. In this, there is a vertical air flue 45, having partitions 46, vvhielrserve to support the flue gas lues 14, and in e fect divide the main air Hue l5 into a group of sub-fines 47.

48 indicate the inlet orifices of a. Iseries of fines carrying the air from the upper part of the flue 45 to the secondary air nostrils of the furnace.

The method of operating the apparatus is as follows: A fire is started on the grate 2 of producer 1, and fuel is gradually charged into thefproducer through the chute 43 until a depth of from three to six feet has been attained, air in limited quantity mixed with water vapor being introduced beneath the grate 2. The oxygen of the air and water reacting with the fuel forms producergas. AThis escapes from the producer through the ports 5, mingling with lheated air which enters through the nostrils 29, and burning in the combustion chamber of the. retort oven 6. The products of this combustion pass around the retorts 7; carbonrain; the coal therein, and escape from the retort oven through the orifices 8 opening` into the lues i-one on either side of the oven. In normal working these two currents of products or combustion (which I shall hereafter roter to as fine gas) are equal in volume. By .keeping the volume of ilue gas passing through the two flues 9 equal, a uniform circulation of the products of combustion through the retort oven is insured. If now it is seen that under normal conditions of working one recuperator is hotter than the other or-f-putn ting it another way-that the are escaping to the chimney tlue at a higher temperature on one v`side than on the other,

,proper manipulation of the by manipulating. the dempers,` 1G and 33, the liuc gases can be distributed between the two recuperators in proportion to the quantity of heat required in each. If the heat required in the secondary recupe ator is greater than the heat required in the primary recuperator the method of adjustment is as follows: After the dampers 32, and 49 have been adjusted so as 'to secure a uniform draw of gases from the two sides of the retort' oven, the damper 16 is opened wider, and the damper correspondingly closed. The result is that the resistance to the passage of the gases through the lues 31 has been increased and that through 14 diminished. In consequence a portion of the flue gas previously passing through 31, diverted to 14 through the cross flue l1 until equilibrium has been established. By dempers the two currents of flue gas are so proportioned that the gas escaping to the chimney flues, leaves both recuperators at the same temperature. It the heat requirement in the primary reeuperator damper closed.

The air enters the recuperator through an adjustable damper 1"?, passes through the flue to the back ot the rccuperator, thence through the tlues 3S. The air current is heated by the tlue gas, passing through the tlues 31, and in passing over the water in the pans evaporates the same. rl`he overflow from the upper pans, dripping onto the flues 31 (which are o1c metal having a relatively high conductivity) greatly aids in the abstraction of heat from the flue gas, and the dcvifle promotes the rapid evaporation ot the water.

It is to benoted that by keeping` the air in Contact with water until it has reached a comparatively high point in the recuperator, where the temperature ot' the heating gases is high, I insure the evaporation o1" a much greater proportion ot' water into the primary air than is possible with the old method ot' maintaining a body of water in the ash pan. By mv method the amount of heat imparted to the water is increased as the temperature ot the air, and therefore the quantity ot' vapor formed is increased as the. vapor cz'urying' capacity ot the air is increasel, Therefore the rate of evaporation ot the water is increased with the vaporcarrying capacity of the air. In the upper ilues the mixture of air and water vapor is subjected to further heating and, owing to the presence of the comparatively high 'proportion of water -vapor, rapidly absorbs heut from the hot combustion gases passing through the times 31. The flue. gas passing through the inner [lues gives up the greater part of its sensible heat to the,` .ve.ter*tn.d air.

is the greater, thc

The current of mingled air and water vapor passes through' the recuperator, being highly superheated in' the upper liues thereof, and leavingr the recuperator 3 through the opening?,n ll passes through the liuc a2 into the ash pit of the producer. Passing up through the fuel bed the oxygen of the air and water combines with the carbon. to forni producer gas. This gas passes through the opening 5, mingles with the secondary air entering through the nostrils 29 and burns.

The secondary air enters the recuperator l throughsj damper 17', passes to the back of the recuperator through thellue l8,thence back and forth through the flues 19,'talting' up heat from the lue gas., at the same time missing through the llues 11i. llroni the uppermost liuc 19 the heated air passes through the port 2O into the equalizinp; flue 2l. AFrom 21 it passes through the series of ports 22 into the distributing flue These openn ings 22 have movable tiles 24 covering them. Bv inserting;n an iron rod` through an appropriate handhole at the front end of 23, the tiles 24 can be adjusted over the orifices 22 in such a way that the flow of air from 2l is uniform along,` the Whole length. From the air passes up through a series of flues 25. These tlues 25 are connected with openings 27 into an equalizing flue 28, and with cross-fines 26, in the keys of themroducer arch. A portion of the heated air passing through 25, enters the corresponding cross'- fines 26 and passes into an equalizinpg liuc 28 on the left-hand side of the retort oven. From. 28 the air passes to the nostrils 29.

lt is evident that l am not limited to the relative location of the air recuperators shown. Their relative positions may be the reverse of that shown without inlany Way chaincqing1 the principle of operation.

Mv invention is not limited in its applica tion to the particular type of vapparatus shown` via-an apparatus for the manufacture of illuminating; gas-but may be used in connection with numerous different types of furnaces in which the gas producer and furnace for the combustion of the gas have similar relations to each other.

L The usual construction of a gas bench is such. that it furnishes ideal conditions for the application of my invention thereto, but

the invention may be applied With great advantage to' Zinc furnaces, re-heating furnaces, etc., and to all furnaces of the same general type.

The reaction o n ivhich the formation of producer mainly depends is that occurring When carbon is burned with an amount of oxygen insufficient for complete combustion, viz., C2+O2=2C0- This reaction is a highly exotherniic or heat producing reaction, about 44:50 B. T. U. being liberated for every pound of carbon so consumed.

Unless some means is providedfor absorbn ing the surplus heat, thus generated, the temperature of the fuel bed would rise to a point suilicient to more or less completely sinter the ash of the fuel, forming large masses of so-called.` clinker., Besides, the high temperature is very hard on the walls of the producer itself; the clin'ker attaches itself to them, and when the doors are opened for the purpose of cleaning, the' '1nrush of cold air ,causes a chilling and har.- dening of the clinker, which attaches itself iirmly to the walls and inustnbe removed For these reasons, and' fuel bed. This may be either Water vapor or lproduct-s of combustion.

In this present invention, l use the former of these two heat absorbingmediums. The reactions which take place in the fuel bed in this case are,

` per pound of the latter consumed, leaving' a net absorption of about 5890 B. T. U.

By properly proportioning the amounts of air and. water vapor supplied to the fuel bed, it is plain that l can exercise a control over the temperature of the producer.

Besides the advantage of being able to control the temperature of the fuel bed, there is also another important advantage in burning the carbon by the oxygen of the water. This is the saving of heat to the furnace that is effected by so doing.

In nearly all furnaces used for ordinary metallurgical and manufacturing operations there is a fixed minimum for the temperature at which the products of combustion may be discharged from the furnace. This minimum is fixed by the temperature re; quired for the operation for Which the furnace is designed. l/Vc can never, therefore, use directly in the furnace itself all the heat that is' generated therein. We must invariably carry out of the furnaceall the heat which is carried by the products of combustion at their temperature of discharge from the furnace. This heat can only be returned to the furnace indirectly, by using it 'to heat the air, or gas and air,

EST AVAILABLE COPY supplied to the furnace, o1', in some cases, Now, in the operation of a gas plant, it

the charge for the furnace. Now, since the is the practiceto charge and draw the re- {ggzlniount 0f heut carried by the produsgofj; Vtorts at regular and uniform intervals. The

combustion at any temperature depends unequal distribution of the gases would re- 5 npon tiipyeight; und specific h p'jdut, d "we n vansnluedf 01 ting i rf ' said currents of 'produdt I"of combustion f through` yanother reeperator 'to heat air supplied for .the combustion of 'gas produced in the gasptducing apparatus, the relative volumes of the said two currents of products of combustion being proportioned to th'quantity of heatrequired by the respective air currents, passing the air supp ied to said gas-producing apparatus while said air is in process oi eating in contact with Water whereby the saidair current is lloaded wi Water vapor, superheating the mixture of air and water vaporso produced by the iirst of said currents of products of combustion, introducing the. superheated mixture into said gas-producing apparatus zo to generate producer gas', and burning said gas by means of the air heated by the second of'said 'currents of products of combustion.A 4 i The method of pperating a gas-heated Yfljifu,rnacfewhich comprises' heating the air supplied for n'xaintaini'ng combustion in the gas producer of said furnace bj.' a current of hot.

products of mbustion discharged from said furnace, adding water vapor to .the said air "i5 currntwhile the same is being heated, the lsaid water vapor being addedin a plurality 'of portions, the magnitude of said portions of water vapor increasing with the-increased vapor-carrying capacity of tliesaid air current introducing tho mixture of air and 'water vapor into the said gas producer to generate producer gas, heating a second current cfa-1r by a second current of hot products of combustion, conductingthe said sec on yl"1'rrent .,of air and said producer gas int fid furnace and-burning the said 'gas the eingrljwithdrawing the products of the said combustion from said furnace as two apparatus, the relative volumes of the two substantially equal currents and ,thereafter adjusting the relative amounts of products in said currentsby transfer' from Yune tu the other, 'the relatvevclunies of the two currents proportioned to the relative quantities of heat required in the heating of he respective airv currents.

3.' Theprocess which comprises Withdrajw= ing the products of combustunfroin the furnace chamber of a gas consuming appa; rat'us in a plurality of portinswof equal volume along the; length of said furnace" chamber in 'suon manner as to produce a 'substantially uniform iow at the various points and thereafter producing from suchy uniform portions two currents o f products of combustion of adjusted relative Volume by transfer of products of 'combustion iiitni one auch current to the other auch current,

passing the first of said currents throng a recuperator to evaporate and heat the Water and 'te heat the an supplied [tu a gas profi duting apparatus, passing. the second of said currents 'through vanother recuperator to hfeat the air supplied for the combustion of the gas 'produced in the gas producing currents being proportional to the amount of heat required by the respective air currents, pas-sing the airnsuppl'ied to said gas producing apparatus jwliile said air is in process oi heating in contact with water, whereby the said air current is loaded with water vapor, superheating the mixture of air and water vapor so produced, introducing the superheated mixture into said gas producing apparatus to generate producer gas, and burning said gas by means of the air heated by the second of said currents of products of combustion.

Signed at New York city,`in the county oi New York and State of New York this 90 30th day of March 1909.

HENRY L. DOHERTY. o

Witnesses 'LOUIS F. Marsan, FRED I. SMITH. 

